Bangladesh plans to allocate more land for camps housing Rohingya refugees as concerns grow over a possible outbreak of disease in crowded, makeshift settlements clustered at the country’s southern tip.

About 625,000 Rohingya Muslims have fled to sanctuary in Bangladesh from violence, looting and destruction in neighboring Myanmar after government forces launched a crackdown on August 25, Reuters wrote.

The swift exodus has taken the Rohingya refugee population to 837,000, making Bangladesh one of the world’s largest, most crowded settlement of asylum-seekers.

More than 60 percent of the water supply in the camps is contaminated with bacteria as temporary latrines overflow into hastily-built, shallow wells, a World Health Organization survey showed. Faecal sludge in the settlements goes largely untreated.

“There is a high risk of a public health event, not just cholera and acute watery diarrhea,” said Naim Talukder of the group Action Against Hunger, who is coordinating the efforts of 31 groups and agencies to manage water, sanitation and hygiene.

Most refugees live in flimsy bamboo and canvas shelters in an area crowded well beyond emergency standards, said Graham Eastmond, an official of the International Organization for Migration (IOM).

“You are talking a third of the international standard,” he said. “We need to decongest urgently and obviously, to do that, we need more land.”

The IOM is among the bodies that have urged Bangladesh to free up more land and allow a wider spread of settlements.

“The government already allocated 3,000 acres of land for the Rohingya,” Shah Kamal, a disaster management official, said. That figure is equivalent to 1,214 hectares.

“Considering the current situation, the government is planning to allocate 500 acres more land for them,” he added.

Last week, Bangladesh approved a $280-million project to develop an isolated and flood-prone island in the Bay of Bengal to temporarily house 100,000 Rohingya, despite criticism from rights groups.